The present invention relates to a drive for a plastic injection-molding machine having a rotary drive for driving a worm shaft to perform a rotation and a linear drive for driving the worm shaft to perform a linear movement in the axial direction in relation to the rotary drive, the rotary drive being capable of being displaced linearly by the linear drive. Such a drive is known from DE 198 52 513 B4.
In plastic injection-molding machines with a worm, the worm is moved in rotary fashion for the purpose of plastifying the plastic granules. The injection-molding process is achieved by a linear movement of the worm, which is typically realized by a hydraulic motor.
In this regard, the document DE 43 44 335 A1 has disclosed a corresponding injection-molding assembly for an injection-molding machine. This injection-molding assembly substantially comprises a worm cylinder, a worm and a worm drive comprising two electric motors, one electric motor being provided for the rotary driving and the other electric motor being provided for the axial movement of the worm. In order to achieve a compact design whilst simplifying the force transmission devices in the worm drive, the invention proposes arranging the two electric motors with their axes aligned with the axis of the worm, at least one electric motor being in the form of a hollow-shaft motor.
DE 101 35 516 A1 has disclosed a drive apparatus for the injection-molding unit of a plastic injection-molding machine which comprises an electromotive drive unit, which has a linearly movable output element and an electric motor, and a plurality of piston/cylinder units. The manner in which the piston/cylinder units function is very complex. A rotary drive acts at a point which is coaxially upstream of a first piston/cylinder unit.